Sperm Whale

Genus: Physeter
Species: macrocephalus

The sperm whale, which made its biggest public splash in the guise of Moby Dick, was hunted for centuries for oil taken from reservoirs in its massive head and rendered from its blubber. The species was especially beleaguered by whalers from the end of World War II until 1985, when the International Whaling Commission created a treaty among its members that virtually stopped sperm whale hunting.

The species is still recovering, though its numbers are likely increasing. Nonetheless, whaling--which targeted large males--so severely affected the species that males today are rarely more than 60 feet long (historic records suggest they once may have exceeded 70 feet).

Description: The sperm whale, also called "cachalot," is generally gray with wrinkled, prunelike skin covering a torpedo-shaped body. The blunt head accounts for a third of its body length and much of it is filled with a waxy, oily substance called spermaceti that lies above and ahead of the skull. This substance once was used for fine lubrication and for fueling lamps.

Whales are mammals, which means the sperm whale has lungs and breathes air. It inhales and exhales through a blow hole located toward the front of the head. The exhalation is misty with condensed moisture, usually projects forward and is characteristically bushy shaped, making it one means for identifying the species.

The tail, which is plainly visible when the animal goes downward head first for a deep dive, is triangular when seen from top or bottom. Each sperm whale bears 20 to 26 banana-shaped teeth on its lower jaw that fit into sockets in the upper jaw. Upper teeth are rudimentary and may not show, but lower teeth may weigh as much as 2 pounds.

Size: A large male may grow to more than 60 feet, females up to about 40 feet. The sperm whale is the largest of all toothed-whale species. Its closest rival in size among toothed whales is Baird's beaked whale, which grows to about 40 feet long.

Diet: Fish and squid, including giant and colossal squid that grow more than 50 feet long

Typical Lifespan: 70 years, perhaps longer

Habitat: The sperm whale prefers ice-free waters at least 3,300 feet deep. When hunting squid, a whale may dive in excess of 6,500 feet--more than a mile--and can stay under for more than an hour.

Range: The species occurs throughout the world's oceans and in the Mediterranean Sea. Prior to whaling, sperm whales may have numbered 1.1 million worldwide, according to the American Cetacean Society; today they number perhaps 300,000.

Communication: Little is known about sperm whale communication. The animals are capable of producing clicking sounds that are roughly equivalent in volume to a rifle shot and rank among the loudest animal sounds. Such sounds may be used as a form of sonar to locate prey. The large head and its oily filling apparently help the animal to direct or aim its clicks. Some divers have reported feeling pulsations, probably from sound, emanating from nearby sperm whales.

Life History and Reproduction: Much of the sperm whale's life is spent under the sea far from land, so the species remains largely a mystery. Individuals are born into groups composed of about a dozen females and their young.

Like elephants, females tend to stay together, but males leave the group as early as their fifth year. Young males form groups with others about their age. As they mature, the males break into smaller groups; older males usually live alone.

The bulls tend to stay in cooler, higher latitudes, while females remain in warmer waters. Males are ready to breed at 18 years old but don't reach full size until about 50. They return to female ranges to mate.

Females are sexually mature at 7 to 13 years and produce young at intervals of 3 to 6 years, with gestation lasting 14 to 16 months and usually resulting in a single baby. Females will cooperate in defending young from dangers such as orcas and also will suckle one another's young.

The Gulf of Mexico Sperm Whale

A small population of fewer than 1,500 sperm whales lives in the Gulf of Mexico; the species was much more numerous there before whaling put a dent in its numbers.

Federally listed as endangered, gulf sperm whales spend much of their time along the continental shelf and in the Mississippi Canyon, a region of deep water off the river delta where prey concentrates. Females and juveniles in particular reportedly favor this area.

The whales feed on fish and squid, including giant squid , such as the 19-foot, 103-pound specimen captured in the gulf by researchers in September 2009.

Studies have found that gulf whales are a distinct population. They use combinations of calls different from those of other sperm whale populations and are smaller in size, probably an adaptive response to the limitations of their habitat and its food sources. This population stays year-round in the gulf.

Oil and Sperm Whales in the Gulf of Mexico

For years now, biologists have feared that oil development in the gulf could harm sperm whales. During the past decade, oil companies have been drilling in increasingly deeper waters. The Gulf of Mexico is studded with 4,000 offshore oil platforms and holds 25,000 miles of active petroleum pipeline; the platforms and various exploratory activities are focused on the Mississippi Canyon and continental-shelf edge favored by sperm whales.

Consequently, the federal Mineral Management Service, which grants drilling permits to oil companies, has administered several studies during the past few years to understand how whales behave in the Gulf.

"We first started this directed sperm whale work in 2000, and that is because industry was moving into the waters out there, and we frankly needed to know are those kind of activities a determent or an impact to sperm whales," Carol Rodin, an official with the service, told a reporter for Mississippi Public Broadcasting last March.

These studies were funded by the oil industry, however, and yielded reportedly inclusive results about the potential dangers that oil development poses to gulf whales. Moreover, in 2004 some studies were canceled or reduced in scope by the service and its industrial partners.

However, late last winter federal researchers did sail the gulf to collect data on sperm whales and particularly on their prey species.

Studies have suggested that loud sounds used by the oil industry to detect oil deposits under the gulf floor may interfere with the whales' use of sonar to locate prey. To avoid conflicts with hunting whales, the oil industry said it would not use its noisy exploratory techniques within a third of a mile of sperm whales.

How Does the Gulf Oil Disaster Threaten Sperm Whales in the Gulf?

The Gulf Oil Disaster poses several threats to sperm whales and to other whale species in the gulf, as well as to dolphins.

• Oil floating at the surface can emit toxic fumes that surfacing whales and dolphins will breathe.

• Oil can coat baleen--comblike growths in the mouths of toothless whales used for filtering prey out of ingested water--and make it ineffective for capturing prey.

• For sperm whales, which are not filter feeders, the biggest threat from the BP oil disaster and from the toxic chemical dispersants used by BP to break up the oil is the harm that may be done to prey species deep under water.

• Even if not killed outright, prey animals are likely to absorb the toxins and pass them on to the whales. This factor could impair reproduction in both whales and their prey.

"The spill was from the gulf floor, so contamination of the entire water column, from top to bottom, is a very grave concern for all marine life in the area," says Doug Inkley, NWF senior scientist.

Threats to Gulf of Mexico Sperm Whales

The sperm whale is federally listed as endangered under the Endangered Species Act. The animal is safeguarded in U.S. waters by the Marine Mammal Protection Act and worldwide by international whaling agreements. Because few are killed by hunters yearly, future prospects for this species are promising.